Viscose modification



"films cast from the various viscoses.

for five minutes and weighed in a closedb'ottle.

United States Patent Pont de Ner'nours and Company, Wilmington, net, a corporation of Delaware No Drawing. Filed May 14, 1956, Ser. No. 584,450

l 13 Claims. 01. 18-54) This invention relates to the production of improved regenerated cellulose structures and especially filaments, yarns, cords and the like having improved physical properties. More particularly, the invention relates to the reduction of the primary swelling of gel :fila'ments from viscose with substantial improvement in filament and yarn properties.

An object of this invention is to provide new and effective modifiers for viscose which -will .permit the manufacture of regenerated cellulose filaments, yarns, cords and the like exhibiting considerably improvediproperties as compared with filamentous products produced from unmodified viscose. Another object of the invention is to provide a yarn manufacturing process from modified viscose which yields filaments having low gel swelling values, high tenacity and a high proportion of skin. Other objects will appear from "the description that follows:

These objects are accomplished by adding to viscose or the viscose forming materials, at least 0.06% of a selected ether ethanol or diether of the general formula:

where R is alkyl or-aryl; n is 'aniritegerof from 1 to 4, inclusive, and R is hydrogen, alkyl or 'aryl; and extruding the resultant viscose into an acid coagulating bath which preferably contains up to Zinc sulfate. Preferably the coagulated filaments or the like are subjected to the action of a secondary hot bath and stretched before winding them up. By selected ether ethanol or diether is meant one which is soluble in 6% aqueous 'sodium hydroxide to the extent of at least 1% and no more soluble than 0.5% in the coagulating bath.

The invention will be more clearly understood by reference to the examples and discussion which follow. These examples are given for illustrative purposes only and'are not to be construed in any sense as limitative. The invention is generally applicable to the preparation of filaments, yarns, cords, films, caps, bands, ribbons, and other structures of regenerated cellulose, but for convenience is discussed with particular reference to the production of viscose rayon yarn.

el swelling are determined in both yarns spun and The numerical values of gel swelling given below for various yarn samples are usually determined according to the following procedure. The gel yarn is collected from the first feed wheel without stretch and prior to the hot dip bath by allowing the yarn to drop onto a square of cheese cloth for 3 minutes. The sample is centrifuged (3600 r.p.m.) The sample is washed free of acid, dried in an oven at 105 C. and weighed. The ratio of the gel weight to cellulose hydroxide.

after l /2 hours.

2,962,341 Patented Nov. 29, 1960 weight (grams of gel per gram of cellulose) is referred toas gel swelling (yarn). Variations may be introduced in the procedure, e.g., in the stretch, spinning speed or length of bath travel, but these introduce only minor changes in the numerical values of yarn gel'swelling. 'Gel swellings and D values mentioned in Examples 9-11 and 13-15 are determined as in US. 2,536,014. M An alternative method of determining gel swelling is from films cast from the viscose. Films of modified and unmodified viscose, 15 mils thick cast on a glass plate, are coagulated in 18.5% sulfuric acid'17% sodiumsulfate-l0% 'zinc sulfate bath at 60 C. A sample of'each coagulated film is cut from the center, centrifuged and weighed. The weighed samples are then washed free of acid and salt, dried overnight at 105 C and reweighed. Gel 'swellings (grams of gel film per gram of cellulose) are determined for both modified and unmodifiedfilms. The ratio of the :gel swelling of the test item to the gel swelling of the unmodified viscose film is calculated. This numerical value is called the gel swelling ratio (films). In all the examples the caustic contentrefers to the total alkalinity expressed as sodium It includes the free sodium hydroxide and that combined in the form 'of sodium carbonate, "sodium .trithiocarbonate, and sodium cellulose xanthate.

EXAMPLE I A 5% cellulose and 6.5% total sodium hydroxide v'iscose modified 'with 0.5% phenoxyethanol (based on total weight of viscose) is prepared ih "the following manner. Alkali cellulose aged to the desired viscose viscosity (40 to 60 poises) is xanthated for 2 hours using 43% carbon disulfide'(based on air dry cellulose). The xanthate crumbs are dissolved in a solution of caustic, to which mixture the phenoxyethanol is added After mixing for a total time of 3 hours at 17 C. the freshly prepared viscose is filtered, deaerated and kept at 4 C. until spun; i.e., it is spun in the unripened state as shown by'the high sodium chloride salt index value (16.0) and high xanthate sulfur content (1.35% V A yarn of 1100 denier-720 filaments (0.0025" spinneret hole diameter) is spun into a primary coagulating regenerating bath, consisting of 6.5% H 17.8% Na SO and 9.5% znso... The apparatus and general procedure used to spin the yarn described above are essentially the same as those used commercially in the so-called bobbin or spool spinning process. The specific conditions include a primary bath travel of 41 inches, a

480 inches per minute, and a hot dip treatment in a 2% H 80 bath at 98? C. after which 100% stretch is applied prior to collection on a bobbin. The resulting regenerated cellulose gel yarn is washed free of acid and salt, wet slashed, twisted to 3 turns per inch and tested after suitable conditioning. Some of the slashed yarn is plied to an 1100/2 construction, i.e., two strands of 1100 denier yarn are combined to make a cord. The .cor'ds are then tested after being conditioned in az'fashion similar to the yarn.

The properties of the yarn and cord prepared as described herein are listed in Table I below. Yarn gel swelling values are also given. Not only is there an increase in cord tenacity and a lowering of gelswelling produced by the practice of this example of the invention as compared with results obtained by spinning unripened unmodified viscose, but-there is an increasefin the amount of skin as measured in yarn cross-sections.

Table 1 Un- Modified modified Bath Acid Yarn Properties:

Tenacity, dry, g./d Tenacity, wet, g./d Tenacity, loop, g./d Elongation, dry, percent. Elongation, Wet, percent Elongation, loop, percent- Gel Swelling Cord Properties:

Conditioned Tenacity. g./d Oven-Dry Tenacity, g./d

EXAMPLES II-VII Additions to viscose of ethoxyethanol, butoxyethanol, phenoxyethanol, methoxyethoxyethanol, butoxyethoxyethanol, and phenoxyethoxyethanol gives similar property improvements in the spinning tests using the conditions set forth below which are substantially the same as given in the preceding example except for minor differences in spinning bath acidity. The properties of the yarns and cords obtained and the gel swelling values measured by use of these ether ethanols are summarized in Table II.

4 EXAMPLES IX-XI As previously indicated, improved results are obtainable even though the coagulating bath contains no zinc sulfate. This is shown in the series of runs recorded below in Table IV as Examples IX-XI. The viscose used is unripened and contained 7% cellulose and 6% NaOH. The coagulating regenerating bath is composed of 11% sulfuric acid, 27% sodium sulfate and the balance water.

While excellent results are obtained by modifying the viscose with one or more of the ether modifiers of this invention one or more other modifiers may be mixed into the viscose therewith. For instance, polyethylene glycols, preferably with a molecular weight of from 300 Table II YARN AND CORD PROPERTIES FROM VISCOSE MODIFIED WITH VARIOUS ETHER ETHANOLS [5% cellulose, 6.5% NaOH, 43% CS2 viscose; 8.5% F2804, 17.5% M11804, 9.5% ZnSO; bath] Yarn Properties Cord Properties,

Tenacity, g./d.

Example Modifier (0.5%) Tenacity, g./d. Elongation, Gel

percent Swell.

Cond. Oven- Dry Dry Wet Loop Dry Wet Loop unmodified 4.62 2.91 3.27 9.8 18.8 6.8 2.35 3.51 3.85 ethoxycthanol.-- 4.65 3.02 3.39 10.0 21.1 7.7 2.19 3.66 3.94 butoiyethanoln 4.64 3.18 3.51 10.9 21.2 8.4 2.14 3.70 4.01 phenoxyethanol 4.89 3.27 3.57 10.7 21.3 8.1 2.06 3.86 4.20 methoxyethoxyethanol. 4.56 3.14 3.48 10.9 21.4 8.6 2.10 3.67 3.92 butoxyeizhoxyethanol 4.65 3.03 3.45 10.8 22.1 7.9 2.08 3.73 4.11 phenoxyethoxyethanol.. 4.69 3.12 3.57 11.5 22.9 8.7 2.04 3.86 4.09

EXAMPLE VIII 45 to 1000, the amines disclosed in Cox US. Patent 2,535,-

An unripened viscose containing 7% cellulose, 6% sodium hydroxide and 1% of ethoxyethoxyethoxyethanol (C H OC H -OC H OC H OH) is prepared and spun into a coagulating regenerating bath consisting of 9% H 14% Na SO and 13% ZnSO in the manner described above under Example I. The properties of the yarn produced and gel swelling values are given, together with results from an unmodified control run, below in Table III.

Table III Tenacity, g./d. Elongation,

percent Gel Swell- Dry Wet Loop Dry Wet Loop Controlyarn 3.50 2.03 2.70 5.8 13.3 3.7 3.32 ModifiedYarn 3.56 2.00 3.01 6.4 13.2 4.9 2.85

044 or diamines such as hexamethylenediarnine, N,N'- dimethylethylenediamine and tetramethylenediamine may be combined with the ether modifiers of this invention to produce yarns and cords with substantial increases in physical properties and a lowering of gel swelling. An example of an ether ethanol in combination with polyethylene glycol and cyclohexylamine follows.

EXAMPLE XII A 5% cellulose-6.5% sodium hydroxide viscose is modified with 0.5% butoxyethanol, 0.2% polyethylene glycol (M.W.=300) and 0.1% cyclohexylamine. The viscose preparation, spinning conditions, bath, yarn purification and slashing and yarn and cord testing are as specified in Example I. Yarn and cord properties are given below in Table V along with those of an unmodified control.

Table V Unmodified Modified Bath Acid Yarn Properties:

Tenacity, dry, g./d Tenacity, wet, g./d Tenacity, loop, g./d. Elongation, dry, percent. El ngation, wet, percent Elongation, loop, percent Gel Swelling Cord Properties:

Conditioned Tenacity, g./d Oven-Dry Tenacity, g./d

mean:

it"has been demonstrated in the f oregoingexamples that theet he'r' eth'anols of this invention'markedly reduce gel swelling and that'the reduction in gel swelling is accompanied by increases in yarn and cord "strengths and other physical properties. In particular; it 'has been shown that the modified yarns with low 'g'el swelling give a much higher conversion of yarn=:str ength to cord strength than do yarns from unmodified viscose- In testing numerous compounds as to their ability to. modify viscose and thereby 'pioduce improved *yar'n' properties a number of other -sim-i-lar compounds are tested.

Film gel swelling, bath solubility and 6%"aqueous NaOH solubilitytests are made on these as' 'well as on the compounds mentioned above. Althoiighyarn gl s'welli rigs and film Y gel swellings do not always -cor"relate, generally the modified potentiality or acornpound maybe 'judged from this test. The film gel swellin'gratio (ratio of modified gel swelling to unmodified gel swelling) of the.

compounds tested aregiven in Iable VI. Only the value of the optimum concentration (0.5% or 1%) for each 20 compound is given.

glycol diethyl ether, tetraethylene glycol diethyl ether,

-andtriethy1ene glycol dimethyl ether. EXAMPLE XIII Viscosecontainiiig028% tetraethylene glycol dimethyl "ethr'is prepared as fo'1lows, using 7% cellulose and 6% sodium hydroxide.

Alkali "cllulos'eage'd to get the desired viscose viscosity (30-60 poises *is xanthated for 3.5 hours in vacuurn using 30% carbon disulfide (based on the recoverable bone-dry cellulose). The xanthate crumbs are dissolved in a solution of sodium hydroxide and after 1.5 hours mixing ata temperature below '15"C.,'0.8% tetra- Table VI Gel Swelling Solubility-1n Solubility Nameand Formula Ratio at -8.5-17.5-9.5 1n 6% (X) Cone. Bath v NaOH v Percent 1 methoxyethannl 0. 95 (110%) CHsOCHzCHzOH W 2' ethoxyethahnl 0.95 (1.0%) 0.4 1

CzHsOCHgCHgOH 3' butoxyethanol 0.71 (1.0%) 0.2 1

C4 QOQH2C 2OH M W M '4 'phelidxyeflirifinl 0.71 (0.5%) 0.1 1

C5H5OCH2CH3QH A, 5 diethyl zlycolether 0:99 (0.5%) 0.2 1

OEHEOOH2OHBOGEHB p H V l "6 z ethylbutoxythanol 0.96 (0.5%) 0.1 (0.6 (C1H5)1CHCH1OCH2CHQOH I M I 7 ethoxyethylacetate 0.87 (1.0%) 02 1 Cz1I5OCHaCHzO'-"OH; V

3 triglycol dichloride 0.91 (0.5%) 0.1 (0.6

(31 0112011 0QHnGHzOOHaCHaOl M1,, 9 glycol diacetate 0.90 (0.5%) 0.1 1

0 CH: OOH 2CHzOCHI -10-..- 'glycoldlformnte 0.99 (0.5%) 2 1 dlglycol chlorhydrlnn 0.89 (1.0%) '2 1 O1CH2CH2OCH2OH2OH Iethenyloxy, Z-methoxyethylene 0. 74 (1.0%) 0.5 1 CH2=C OCHgCHzOCHa ethoxy'ethylaerylate 1.00 (0.5%) 0.1 1

i CH1=CHCOCH2CH7OCH5 methoxyethoxyethanol 0.94 (1.0%) 04 1 c aoczHaooz ioH butoxyethoxyethanoluu; 0.70 (1.0%) *0 .1 1 CAHOOG2I'I4OO2HJOH, phenoxyethoxyethanol 0.62 (0.5%) 0.1 1 O6H5OG1H4OC2H40H butoxyethoxyethylacetate 0. 71 (1.0%) 0.1 1

. v ;-H C4HgOOiH4OC2HlOO'-CH;

'18 'methoxytriglycolaeetate 0:98 (055%) 0'1 '1 OH3OOQH4OC2H4OC1H4OU-CH3 v V 19 ethylene-bls(capryloxyethyl) ether 0.89 (1.0%) 0.1 0.5

n if i 'C1H 5 OOCzHZOCiHAOCzHZOC OiHiE The modifiers abdve marked with an asterisk("" come within this invention. I-he -others-are-givento"illustrate 75 -prepared-viseoseis-fi1tered while it is cold, deaerated, and

ethylene glycol dimethyl ether is added. The freshly- 7 kept at .C. until spun, i.e., it is spun in the unripened state andhas' a'high salt index value, high xanthate sulfur content, and fairly low sodium trithiocarbonate content.

.The' viscose isspuninto 275 denier-100 filament yarn by demonstrating the improvement brought about by the viscose modifier. In the case of the zinc bath, skin thickness of the yarn is greatly increased by the modifier. With zinc-free bath, the yarn from the modified with and without zinc sulfate. The zinc-free bath contains 11% sulfuric acid and 27% sodium sulfate while the zinc bath contains 8% sulfuric acid, 14% sodium sulfate, and 13% zinc sulfate. The yarn is given a bath travel of 30 inches using a roller guide. The apparatus and general procedure used to lead viscose into the bath and to collect the formed threads are essentially the same as those used commercially in the socalled bobbin or spool process. The specific conditions I 5 viscose has a much thicker skin than that from the un- Iby extruding through a spinneret having holes of 0.0025 d d i s and is generally noncfemllated- Table VII Modifier 0.8% Tetraethylene glycol None 0.8% Tetrnethylene glycol dlmethyl None dlmethyl ether ether Bath 11-27 (HaSOiNanSO4) 11-27 8-14-13 (H:S04N81S04ZI1SO4) 8-14-13 D Value Tn 4.0-. 2.5 4.0 2.5 Gel Swelling 3.2 3.7 3.2 Tenacity, g./d.:

Dry 3.7.. '3. 5 4. 4 We 2.3---. 2.0 2. 8 Elongation, Percent:

Dry 7.1.- 4.4 5.7 5.6 We 16.8-- 9. 6 15.5 10. 5

diameter and primary coagulating and regenerating baths, EXAMPLE XIV A viscose containing 1% diethylene glycol dimethyl ether is prepared and spun in the manner described in Example I. In this case, however, the viscose is allowed to ripen slightly and in the case of the zinc bath a higher acidity is used. The properties of these yarns along with those from unmodified control viscose are described in the table below. Yarns from viscose containing this modifier showed improvements similar to those obtained with tetraethylene glycol dimethyl ether.

Table VIII Modifier Dtethylene gly col dimethyl None Diethylene glycol dtmethyl ether None e er Beth 11-27 (H:SO4-NB2SO4)- 11-27 9.2-1 1-13 (HiSO4NaaS04-ZnS0l) I) value, In 3.8 2. 5 3.3 Gel Swelllng---.- 3 2 3. 5 3.1 Tenacity, g./d.:

Dry 3.5-. 3.4 3.6 Wet 2.3 1.9 2.3 Elongation, Percent:

Dry 7.5- 5. 8 6.9 6. 8 Wet 16.1 10.2 13.5 13.3

include a bath temperature of C. and filaments are carried through a secondary bath of 1% sulfuric acid at 95-400 C. The yarn is wound on a bobbin at 28 yards per minute with the stretch obtainable at of the break tension. The resulting regenerated yarn is washed free of acid and salt and then dried. After twisting, the yarns are tested at 21 C. and 60% relative humidity.

The properties of the yarns. from this viscose are listed in the accompanying table together with those of an unmodified control viscose. It will be seen that the yarn prepared from viscose containing tetraethylene glycol dimethyl ether has lower gel-swelling value and higher D" value than the control. In general, wet and dry tenacities and elongations are higher than controls, there- EXAMPLE XV Viscose containing 1% butoxyethanol is prepared using 8.2% cellulose, 6% sodium hydroxide, and 50% carbon disulfide (based on the bone-dry cellulose). This viscose is spun into zinc-free bath as described in Example I. The effects of the modifier in this viscose on D value, gel swelling, and appearance of cross-section of the filament are shown in the table below along with those for unmodified viscoses and a modified viscose containing 7% cellulose. It can be seen from the data that the efiectiveness of the butoxyethanol is maintained at increased cellulose concentration and that noncrenulated yarns having high proportion of skin can be prepared at cellulose concentrations above 7%.

Table IX Modifier 1% butoxyethanol N one 1% butoxy- N one ethanol Percent Cellulose- 7 7 8.2-- 8.2. Bath 10.8-27 (H2S04N82S04) 10.8-27 10.2-27 11.6-27. D value, In- 4.5- 2 5 5.0.- 3.0. Gel Swelling 3.1.- 3 2.6. 2.9. Tenacity, g./d.:

Dry 3 R i 4 2.7-- 3.5. We 24 1.9 2.6-- 1.9. Elongation, Percent:

Dry 5.3 5 8 5.8.- 6.1. Wet 18.9.- 10.2-- 17.3.- 12.3. Cross-section Contour Noner n Crenulated.. N oncgig- Crenuleted.

u a skin Think Thin 40-50%,

skin.

see-ash The'cord properties of the'yarns produced in 'Exar'nples XIII-XV are likewise improved as described in previous "examples.

EXAMPLE'XVI Viscoses containing 6.25% recoverablecellulose and 5.75% alkali are prepared from woodpulp sheets in the conventional manner using 38% carbon disulfide, based on the weight of the air dry pulp, in the xarithation step. The viscoses are filtered, deaerated and ripened to asalt index value of 16 to 17 and a viscosity of about 30 poises. Phenoxyethanol, in the amounts indicated below, is addedto-the'viscoses used for the preparation of yarns A, B and C. No modifier-is added to the viscose used for preparing yarn D.

The viscoses are extruded at a temperature of about 44 C. into a spinning bath maintained at a temperature stretch imposed on the yarn up to the feed wheel is about The yarn is-stretched an additional 20% by passing it to a second feed wheel having a larger diameter than the first feed wheel but rotating at the same speed 'asthe first. A'solution of dilute sulfuric acid at a tem- -perature of 90-100 C. is applied to the yarn on both 2 feed wheels. From the last feed wheel the yarn is led -into=a rotating bucket whereit is Wound into a cake at a speed of about'lOOyards per minute. .purified, dried, slashed andLprOcessed into cord inthe The. yarn is'the'n conventional manner.

Properties of the yarns and cords produced in these "tests are shown in the table below. The D.B. fatigue 'values shown 'are obtained in the following manner: cords are conditioned for 48 hours at 24 C. and 54*rela- 'tive humidity and then clamped in jaws at 16.75 inches A B C D Modifier Phenoxy Pbenoxy P enoxy None Ethanol Ethanol Ethanol Modifl'er Added, Percent 0.15 0.10 0.06 Bath acidity, Percent 9.4 7. 5 7. 5 7. 5 Yarn Properties:

Tenac ty, g.p.d., dry 4.79 4. 54 4. 51 4. 27 .ilenac ty, g.p.d., wet 3. 16. 3.00 3. 22 2. 87 Tenacity, g.p.d., loop 3. 24 3. 26 3.20 3. l6 Elongation, percent, dry 10. 4 9.1 11.4 8. 0 Elongation, percent, wet 20. 7 22.0 27. 2 21. 3 Elongation, percent, loop 5. 8 5. 9 6. 7 5. 5 Gel swelling .1 1.92 1.97 1.89 2.11

Cord Properties:

Tenacity, g.p.d., conditioned 3. 3. 43 3. 48 3. 24 Tenacity, g.p.d., oven dry. 3. 98 3. 88 3. 81 3. 48 D.B. fatigue, minutes 287 229 322 08 Low bath solubility has long been considered a primary requirement for viscose modifiers. As evidenced in Table VI above, there are certain other factors which are important: structure and solubility in alkali. There is described in US. 2,040,712 the use of Cellosolves and carbitols in leuco vat coloring matters which are added to viscose. Peculiarly, the process of this patent does not give applicants results; the gel swellin-gs are noticeably higher and the applicants improved yarn and cord properties are not obtained. Apparently dyes of this type interact with the modifiers of this invention in some manner to render them inoperative. Therefore, for effective results with the modifiers of this invention, leuco vat dyes to use more than 2.0%.

the recoverable bone dry cellulose). that higher than normal xanthate sulfur contents (higher "salt indices) can be used in the viscose when the modifiers sulfate.

7 ofthc type described in US. 2,040,712 should be substan- "tiallyab'sent, i:'e., theyshould be-entircly absent orpresent in very small amount relative to the "amount of modifier used.

For effective results the ether ethanols and diethers of this invention should be'used in the viscose at concentrations of at least 0.06% and ingeneral, it is unnecessary Preferably, these compounds will beused in viscose at concentrations of from 0.1% to 1;0% based on the total weight of-viscose.

Theviscose used inthe process of the invention may "be a variety of types; for example, it may be from wood ip'ulpycotton linters, mixtures of the 'two, or even other types'of cellulose. The composition of the viscose may alsobe varied widely. Forexample, it may have a cellulose content of from 4% to 10% or even more and an alkali content of. from 4% to 9% or more. The standard viscoses of the'indus'try, i.e., those having between 5% and 7% cellulose-and between 4% and 7% alkali are fpreferably used. The amount of carbon bisulfide used in xanthation can be 25% to 60% or higher (based on It has been found of this invention-are added and there appears to be an "advantage in stretchabilityand level of the yarn properties if salt indices higher than 5 are used. It is generally necessary to use 30% or more of carbon bisulfide to obgel swelling an'dyarn and cord properties are also obtained with normally ripened viscose.

The composition of the spinning bath is not critical when the modifiers of this invention are present-in the viscose. An improvement in yarn and 'cord properties and reduction of gel swelling are obtained with acid salt baths free of zinc salt or salts of other heavy metals. Of course, when mixed modifiers are used and one of the modifiers is an amine, optimum results can be secured only with baths containing a substantial amount of zinc Useful baths include coagulating regenerating baths containing from about 4% to about 12% sulfuric acid, about 5% to about 25 sodium sulfate'and about 1% to about 15% zinc sulfate.

For optimum spinnability, the bath temperature range should be from 40 to 75 C. The bath temperature as well as the bath composition and-especially bath acid may need to be adjusted depending on the specific modifier or combination of modifiers used and the concentration of these modifiers in the viscose. Optimum results can only be secured by carefully balancing the spinning bath composition with the specific modified viscose at hand together with bath travel, bath temperature and spinning 200 inches or more in the primary bath by means of a multiple roller setup which gradually applies tension to the traveling filaments and thereby orients them while they are still plastic. The preferred method, however, is to apply a part or all the stretch beyond the primary bath in a secondary bath or after the yarn is acted upon by the secondary bath. The secondary bath may consist simply of water or dilute (1% to 3% sulfuric acid) or it may have the same composition as the coagulating bath but at a greater dilution, e.g. one fourth of the concentration of the coagulating bath. The yarn may be given a travel of 10 to 50 inches more or less in the secondary bath of hot water or hot dilute bath. The temperature of the secondary bath is preferably between 50 C. and 100 C. Stretches of to are preferred for producing high tenacity yarn and 20% to 30% for textile type yarns. The amount of stretch ap plied depends on the properties desired for the yarn. While the bobbin process is used in the examples, it

is immaterial whether spinning is by bobbin, bucket or continuous processes. The yarn is washed free of acid and salt after which it may be dried in the form of its spin package or may be withdrawn wet and dried on the run. It may be twister-dried or slasher-dried with suitable controls to hold dry elongation at the desired level.

Spinning may be carried out with the aid of spinning tubes such as described in Millhiser U.S. Patent 2,440,- 057 or in Drisch et al. U.S. Patent 2,511,699. These tubes of relatively small diameter and of substantial length confine the bath filaments in their critical stage of formation so that no substantial tension is imposed on the filaments because the speed of the concurrent bath flow through the tube is maintained only slightly below the speed of the filament bundle passing through the tube. It is thus possible to materially increase the rate of spinning over methods earlier described without substantial sacrifice in the desirable properties set forth above.

The novel and improved yarnsobtainable through the process of this invention can in general be used instead of regular regenerated cellulose yarns for any purpose where the latter are finding applications, more particularly in the textile and tire cord industries. As described and claimed in the Cox U.S. Patent 2,536,014, cross sections of the yarns of this invention also exhibit a preponderance of skin over core, in many cases being substantially 100% skin, and these yarns exhibit greater toughness as measured by greater fatigue resistance and longer life in reinforced rubber products. The combination of high tenacity yarns and a high ratio of conversion of yarn strength to cord strength represents a material advance in the art.

This is a continuation-in-part of U.S. Serial No. 228,979, filed May 29, 1951, now abandoned.

Any departure from the above description which conforms to the present invention is intended to be included within the scope of the claims.

What is claimed is:

1. A process for producing a regenerated cellulose structure having improved fatigue resistance which comprises adding to the viscose at least 0.06% by weight, based on the weight of the resultant viscose, of an ether having the formula:

wherein R is a member of the group consisting of alkyl and aryl, n is an integer of from 1-4, and R is a member of the group consisting of hydrogen, alkyl and aryl, said ether acting to reduce the gel swelling of the structure, extruding the resultant viscose, in the substantial absence of leuco vat coloring matter, into a sulfuric acid coagulating bath and immediately thereafter stretching the resulting structure having the reduced gel swelling;

the said ether being soluble in 6% aqueous sodium hydroxide to the extent of at least 1% by weight and soluble only to about 0.5% by weight in said coagulating bath.

2. A process in accordance with claim 1 wherein n is 1.

3. A process in accordance with claim 1 wherein n is 2.

4. A process in accordance with claim 1 wherein said ether is phenoxyethanol.

5. A process in accordance with claim 1 wherein said ether is butoxyethanol.

6. A process in accordance with claim 1 wherein said ether is ethoxyethanol.

7. A process in accordance with claim 1 wherein said ether is butoxyethoxyethanol.

8. A process in accordance with claim 1 wherein said ether is phenoxyethoxyethanol.

9. A process in accordance with claim 1 wherein sai coagulating bath contains up to about 15% by weight zinc sulfate.

10. A process in accordance with claim 1 wherein said viscose contains about 0.06% to about 2.0% of said ether.

11. A process in accordance with claim 1 wherein the temperature of the coagulating bath is from about 40 C. to about C.

12. A process for the preparation of a regenerated cellulose structure having improved fatigue resistance which comprises adding to viscose about 0.1% to about 1.0% by weight based on the weight of the resultant viscose, of an ether having the formula:

wherein R is a member of the group consisting of alkyl and aryl, n is an integer of from 1 to 4, and R is a member of the group consisting of hydrogen, alkyl and aryl, said ether acting to reduce the gel swelling of the structure, extruding the resultant viscose, in the substantial absence of leuco vat coloring matter, into a coagulating and regenerating bath containing from about 4% to about 12% by weight sulfuric acid, about 5% to about 25% by weight sodium sulfate and about 1% to about 15 by weight zinc sulfate and immediately thereafter stretching the resulting structure having the reduced gel swelling; the said bath being at a temperature of about 40 C. to about 75 C. and the said ether being soluble in 6% aqueous sodium hydroxide to the extent of at least 1% by weight and soluble only to about 0.5 b weight in the said coagulating bath. I

13. The process of claim 1 wherein the stretching of the resulting structure is carried out in a second bath.

References Cited in the file of this patent UNITED STATES PATENTS 2,040,712 Robertson May ,12, 1936 2,065,668 Dreyfus Dec. 29, 1936 2,393,817 Schlosser Jan. 29, 1946 2,535,044 Cox Dec. 26, 1950 2,860,480 Cox Nov. 18, -1 958 FOREIGN PATENTS 541,099 Great Britain Nov. 12, 1941 UNITED STATES EATENT oEEICE CERTIFICATION OF CORRECTION Patent; No. 2,962 34l November 29, "1960 Norman Louis Cox It is hereby certified that error appears in the above mimbered patent requiring correction and 'that the said Letters Patent should read as corrected below.

Column 1, line 37, the formula should-gappear as shown below instead of as in the patent:

I RO-(CH CH O) R Signed and sealed this 6th day of June 1961 (SEAL)- Attestz.

ERNEST W. SWIDER DAVID LQLADD Attesting Officer Commissioner of Patents 

1. A PROCESS FOR PRODUCING A REGENERATED CELLULOSE STRUCTURE HAVING IMPROVED FATIGUE RESISTANCE WHICH COMPRISES ADDING TO THE VISCOSE AT LEAST 0.06% BY WEIGHT, BASED ON THE WEIGHT OF THE RESULTANT VISCOSE, OF AN ETHER HAVING THE FORMULA: 